Bliss Classification Revision
Penultimate draft schedule for Class D-DF Astronomy
Explanatory notes
1. The following draft schedule represents a radical revision of the existing Class D-DF. The
general reasons for making this revision a radical one were given in detail in the 1969 and
1970 issues of the BC Bulletin.
We should like to express our gratitude to Mr. Saifud Din, Lecturer at the School of
Librarianship, Polytechnic of North London, for his invaluable work in drafting all the
initial schedules.
2. The Summary Outline gives a clear view, we hope, of the basic structure of the schedules.
This structure is fully consistent with the basic pattern we are seeking to establish through
the BC as to citation order, filing order, and faceted notation. The demands made by
observance of this pattern, when combined with the substantial developments in the subject
matter of Astronomy and with the considerable expansion of vocabulary and facilities for
synthesis, have resulted in considerable changes of notation, although the general order will
be seen to be reasonably consistent with existing BC. The only major shift in sequence is of
Spherical astronomy (DAN/DAY) so as to bring it after Practical astronomy (DB) and to
collocate it with the rest of Processes and Properties facet in DC.
3. The structure of the class is as follows:
3.1 Citation order
Existing BC, in providing Schedule 10 for the subdivision of any astronomical body by such
factors as Part (envelope, etc.), Property (luminosity, temperature, etc.), Process (rotation,
precession, etc.) indicates clearly that Body is the primary facet to be cited first. Beyond that
the evidence is less clear. If we assume that Bliss aimed (intuitively it would seem) at an
inverted schedule, with the filing order the reverse of citation order, we arrive at an order
which is almost totally in agreement with that of the standard citation order which the
revised BC now tries to follow.
3.11 Standard citation order gives the following:
1. Systems of stars, etc. (galaxies, clusters, etc.)
2. Bodies within these systems (stars, planets, satellites, etc.)
3. Parts of these bodies (surface, envelope, etc.)
4. Processes & properties (radiation, motion, mass, density, etc.)
5. Operations, actions on 1-4 (essentially, observation and measurement)
6. Agents of 5.
i
3.12 Citation order between arrays (i.e. within each broad facet). To some extent the
fundamental Whole-part or Systems-subsystems citation order continues to provide a
solution; e.g. the Earth as a planet belongs to the solar system which belongs to the galaxy
which belongs to the local group (of galaxies in a galactic group). But this does not tell us
the citation order between, say, several different arrays of stars (by stage - novae, dwarfs,
etc.; by spectral type - blue, white, etc.; by other radiation phenomena - variable, quasar,
etc.). if any astronomer users of the schedule think that a more helpful citation order could
be achieved than that in this draft, we would welcome their comment.
3.2 Facet filing order
In order to maintain a consistent general-before-special sequence (Bliss’s principle of
subordination) the schedule is an inverted one; i.e. the primary facet files last, the secondary
facet next to last, and so on. Similarly, within each facet, the arrays are inverted as far as
possible.
Compound classes are formed by ‘adding’ concepts which file earlier to those which file
later; e.g. Radio emissions of the sun and planets = Solar system - observation - radio DDZ
BR; the Venus atmosphere = solar system - planets - Venus - atmosphere DFO FM. This
holds also for compounding between arrays in the same facet; e.g. a variable dwarf star is
DDK JW.
A word of warning is necessary here. The different arrays represent ways of classifying the
same thing; in the case of stars, any given star may demonstrate a whole string of concepts;
e.g. a giant star of a late spectral type (M, R, N, S) may also be a long-period variable.
Theoretically it is possible to achieve a class number which compounds all such attributes,
but this might be a very long one. For most purposes, compounding of two arrays will
achieve a reasonable degree of precision.
3.3
Notation
The schedule is fully faceted notationally, as well as conceptually. Compound classes can
be formed, and in a consistent manner, wherever facets or arrays contain the constituent
terms. In existing BC this function was performed only partly by use of the Systematic
Schedule 10, which is now replaced by this more comprehensive number-building facility.
3.31 The basic method of number-building is the use of the retroactive notation. This means that
any given class (term) may be subdivided by all preceding terms by direct addition (i.e.
without any special symbol to act as facet indicator). Therefore any enumerated
subdivisions of that term (i.e. divisions peculiar to it - usually kinds or parts of it) must be
given a class number allowing for this: e.g.,
DDF
DDF
DDF
DDF
DDF
H/S
O
T/X
W
DDG
DDG H
Stars
(Parts) e.g.
Surface
(Kinds - by spectral type) e.g.
White
(Kinds - by number) e.g.
Double, binary
Spectroscopic
ii
The reason why the first enumerated division of Double stars does not appear until DDG H
(instead of earlier at DDG A, or DDG B, etc.) is that all preceding terms (belonging to
other facets or arrays) can be applied to qualify Double stars by direct addition; e.g.,
DDG BP
DDG CF
DDG FP
Photography of double stars
Occultation in double stars
Photosphere in double stars
It should be noted that when terms from the same facet (DD Astronomical bodies) are added
to DDG, the second D is dropped; e.g. DDG DFP). This allows the compounding of terms
within Class DD to be done with a minimum lengthening of numbers.
3.32 The notation is used flexibly, to allow maximum brevity in class-numbers by assigning
numbers according to the amount of literature or the prominence of a topic (not always
reflected by its hierarchical status).
3.4
Practical classification
For each book or article to be indexed, the indexer should ask the following questions:
3.41 Does it refer to a particular astronomical body or system? If it does not move on to the next
question. If it does, consult the Astronomical body & system facet in the schedule and if
more than one concept has t be recognized (e.g. a star at a certain stage and of a certain
spectral type) cite these in the order whereby the term appearing later in the schedule is cited
earlier - e.g. , Stars - giant - red DDH OFT.
Now move on to the next question:
3.42 Does it refer to a particular process or property? If it doesn’t, move onto the next question.
If it does consult the process and property facet, and repeat the procedure described in 3.41.
3.43 Does it prefer to a particular method of observation or study? This procedure continues
until all facets have been reviewed in the sequence of the citation order given in 3.1.
4.
4.1
Some theoretical problems
A central problem is the dynamic subject itself. The pace of development in the study of
astronomy is constantly being sustained or even increased by the development of new
techniques and instruments; radio astronomy and space observatories are two formidable
examples in recent years.
4.2
Nevertheless, the areas of imperfect understanding remains vast and many. This is reflected
in the vocabulary to be organized. It was noted in 3.12 that a major principle of
classification in this subject is inevitably that of Whole-part, giving a hierarchy of galactic
groups (the most comprehensive unit of aggregation), galaxies, sub-galactic systems, starsystems, etc. Provision for the general treatment of any notional body or system (from
particles, through dust to planets, stars and galaxies) is theoretically necessary (e.g. the
general idea of a satellite body) whereas study is almost wholly devoted to particular
contexts, notably our own (‘The’) Galaxy, in our own solar system.
From this viewpoint studies of a given star or system, or kind of star or system, would be
located within the containing association, cluster, galaxy, etc. - but it is not always known
which this is.
4.3
A feature of faceted classification which is sometimes a threat to helpful order is the
separation, by facet analysis, of closely related concepts, because of their category relations;
e.g. radiation is a phenomenon in the processes and properties facet, but the radiation
iii
characteristics of a celestial body may define that body (e.g. a variable, a quasar) or may be
used as a method of enquiry (e.g. radio astronomy) - and the concept is distributed over
different facets.
4.4
Some separation is inevitable, of course, in any linear classification and only be remedied in
the long run by a constant awareness of the possibilities of such distributed relatives on the
part of the searcher. The advantages of a faceted structure are then to be found in the
relatively predictable pattern it imposes on the index.
School of Librarianship
The Polytechnic of North London
May 1972
iv
Bliss Classification: revised schedule for Class D-DF SPACE SCIENCES AND ASTRONOMY
SUMMARY OUTLINE
Present BC
D
DAL
DAL 1/9
SPACE SCIENCES
DA
DA 1/9
DAP
DAQ
Astronomy
Common subdivisions (Form)
Common subdivisions (Subject)
History
Theoretical astronomy
Cosmology
DB
DBK
DBP
DBQ
DBR
Practical astronomy: observation and measurement
Telescopes
Photographs
Spectroscopy
Radio astronomy
DB
DBJ
DBP
DBQ
DC
DCD
DCH
DCQ
Processes & Properties
Position, distance = Spherical astronomy
Celestial mechanics
Astrophysics
DD
DDD
DDE
DDE S
DDF
DDF T/X
DDF Y/G
DDG
DDH/J
DDJ
DDJ W
DDK/L
DDK
DDL
DDL N
DDM
DDN
DDY O
DDQ
DDS
DDT B
DDT N
DDW
DDW TB
DDX
DDY
DDZ
DE
DF
DFH
Astronomical bodies & systems
Chemical substances = Astrochemistry
Cosmic matter = Interstellar matter
Satellites (general)
Stars
By spectral type (Red, white, blue ….)
By number
Binary
By stage (Proto-star, main sequence star …)
Novae
Dwarf
By radiation phenomenon
Variable
High energy
Radio sources (quasars, pulsars)
Galaxies & galactic groups
Nebulae
Associations
Clusters
Constellations
Galaxies
Galactic groups
Local group
Galaxies other than The Galaxy
The Galaxy
Stars other than the Sun
Sun and solar system
Sun
Planets & satellites
Satellites
v
DC
DD
DAN
DCC
DDB
D
DDL
,S
DDD
DDM
DDR
DDT
DDS
DDV
DDG
DD
DDE
DE
DF
DFW
DFM
Planets
vi
Existing BC
D
SPACE SCIENCES
See also
DAL
Space technology & astronautics
Space communication
Exobiology (in Class E)
Applications - e.g. Nautical astronomy (in Class UK)
Astronomy
DAL 1/9
DAL 123
158
184
185
D
Common subdivisions as Schedule 1/4 - e.g.
Almanacs, ephemerides
Technical data, collections of observations
Charts, diagrams
Atlases, maps - e.g.
Star catalogues and maps DDF 185
DES
738
741
742
Research
Instruments see DBC
Methods see also DB
751
755
758
Planetaria
Orreries, planispheres
Models, globes
DAQ
DAR
DAM
Descriptive astronomy
DA
DAP
Theoretical astronomy
DC
DAQ
Cosmology (Astronomical)
DAS
Special theories
Divide like Class B Physics - e.g.
Relativistic astronomy DAS AR
DAT
DAT R
T
V
Cosmogony: origin and development of universe
Red shift
Finite, ‘big bang’, evolutionary
Infinite, expanding, continuous creation, steady state
DB
OBSERVATION & MEASUREMENT = Practical astronomy
DD, DDD
DDC
DB
DBC
Instruments
* Instruments are subordinated to the function they serve.
Those given below are too general in application to be
subordinated usefully to any one function.
DBT
DBD
DBD C
E
Conditions of observation and measurement
Constants
Variations
DBN
DB1
H
J
Errors
Adjustments, corrections
1
[Adjustments, corrections]
DBD M
Mounting, positioning
DBE
DBF
DBG
(By radiation wavelength)
Gamma ray astronomy, -ray astronomy
X-ray astronomy
Ultraviolet astronomy
DBH
Optical, visible astronomy
DBJ
Telescope
DBJ D
E
G
J
K
O
DBJ
(Parts)
Lenses
Eye-pieces
Mirrors
Reflectors
Refractors
Divide like Class BI Optics
DBK
(Kinds)
Alignment telescope
Refracting
Reflecting
DBK
DBL
DBM
(By mounting)
Equatorial
Transit = meridian circle
DBL
DBN
Q
Y
DBP
DBP E
F
J
K
Photographic, photography
Cameras
Films
Photometric, photometry
Photometer
DBP
DBQ
DBQ E
G
K
M
Spectroscopic, spectroscopy
Spectroscopy
Spectrophotometry
Polarimeter
Interferometer, interferometry
DBQ
DBQ P
DBR
DBR
Infra-red astronomy
R
Bolometry (slight heat)
DDN
S
T
(Special to sun)
Heliography
Heliostats
DBO
DBR
DBR E
H
Radio astronomy
Noise
Radio telescopes
2
[Radio telescopes]
DBR J
K
L
O
R
V
W
X
(Parts)
Antennae
Horizontal
Disc
Oscillograph
Radar astronomy
(Special to position measurement)
Quadrant
Sextant
Astrolabe
DBS
Other instruments
DBT
DBU
DBU E
F
H
J
Observatories
Terrestrial
Instrument carrying vehicles
Aircraft
Balloons
Rockets
S
DBV
DBT
Space observatories
Artificial satellites = Orbital observatories
* As astronomical equipment only;
see also Astronautics
Celestial
Moon = Lunar
DBW
DBX
DBY
Expeditions
DBU
DC
(PROCESSES & PROPERTIES (of bodies & systems))
DCC
(Bases for observation & measurement)
DCD
DCD S
Astrometry = Celestial coordinates
Spherical astronomy = Positional astronomy = Geometrical
astronomy
DAY
DAN
DCE B
D
F
H
Meridian
Celestial poles
Zenith
Horizon
DAU
K
L
M
Celestial longitude
Celestial latitude
Equator
DAW
“
DAV
N
P
Q
(Characteristics of bodies, etc. observed)
Number, total
Position
Time
3
DDF
DAP
[Time]
R
DCF
DCF F
G
H
P
R
DCG D
F
G
H
K
L
M
N
DCH
Aberrant
Occultation
Eclipse
Solar
Lunar
Phases
Retardation
DBW
DBV
“
Distances
Parallax
Altitude
Azimuth
DDJ
“
DAU
DAU
Perihelion
Aphelion
Perigee
Apogee
Celestial mechanics
See also Gravitation BD; Quantum mechanics BC
DCH D
F
G
J
DCJ
DCJ D
E
G
P
Q
R
S
V
X
DCC
Time
* See also Chronology LF
Sidereal time
Solar time
Chronometers
DBH
Motion
Velocity
Tangential
Transit
Proper
Apparent
Radial
Line of sight
Retrograde
Diurnal
DDP
DCK
DCK E
H
Orbit
Eccentricity, inclination
Perturbation
DCD/E
DCK
DCH
DCN
DCP
DCP L
N
Rotation
Inclination, axis
Precession
Secular variations
DCN
DCP
DCL
DCI
Oscillation
(Special to earth)
Nutation
DCL
O
Q
(Special to moon)
4
[Oscillation]
(Special to moon)]
DCP R
Libration
DCP T
Gravitation
X
Equilibrium
DCQ
DCQ E
F
G
H
DCR
DCR E
G
J
Astrophysics
Physical structure
Dimensions: size, shape
Mass
Density
(By source, origin)
Galactic, interstellar
Stellar
Solar
Interplanetary
S
T
V
X
Y
Primary cosmic radiation
Cosmic showers
Gamma rays, -rays
X-rays
Ultra-violet
DCT
DCT D
F
J
K
R
T
V
DCV
DDI
“
DDE
Radiation
Mechanisms (e.g. Synchrotron radiation)
Cosmic radiation
Radiative transfer
K
M
O
Q
DCS
DCS D
DDB
Light
Colour
Luminosity
Period
Magnitude
Counter glow
Zodiacal light
Infra-red
Thermal
Temperature
Radiofrequency
DCV P
R
Cosmic plasmas
Magnetism, magnetic fields
DCW
Age, life-span
DCX
Astrogeology
DCY
Astrobiology (i.e. astronomical bodies as life support systems)
5
DDK
DDN
DDN
DD
ASTRONOMICAL BODIES & SYSTEMS = Celestial bodies
* N. B. When compounding numbers from DD follow this rule:
Add the divisions DA/DC straight on, as usual (e.g. DDF CQ
Astrophysics of stars). When adding earlier numbers from DDD,
DDE, etc., add these straight on without using the second ‘D’ e.g. DDJ WFH Interior of dwarf stars (not DDJ WDFH).
DDD
Chemical substances, constitution = Astrochemistry
* Divide like Class C
DDE
DDE F
Cosmic matter = Interstellar matter
Nebulae
* Regarded as masses of gas and dust; regarded as masses
of gases, dust & stars (‘extra-galactic nebulae’) see
Galaxies
Gases
Dust
DDE G
J
DDD
(Special to solar system)
* These terms are enumerated here to complete the
theoretically valid array of terms giving the different
aggregations of matter found in cosmic bodies and systems
(arranged by increasing size, from gases and dust to
galactic groups). The literature barely considers these
concepts at the completely general level implied here and
they have therefore been labelled as ‘Special to solar
system.
DDE M
N
P
S
T
Meteors, meteoroids
Meteorites
Asteroids
Satellites
Planets
DDF
STARS = Stellar astronomy
DDF H
O
P
Q
R
RJ
S
SS
T
U
V
W
X
DDD
(Parts)
Interior, core, nuclei
Surface
Photosphere
Spots, faculae
Chromosphere
Jets, flares
Corona
Solar wind (when added to Sun)
(Kinds)
(By surface temperature, giving spectral type)
Red
(Types S, N)
Orange
( “ R, M, K)
Yellow
( “ G, F)
White
( “ A)
Blue
( “ B, O, W)
6
DDM
[Blue]
Y
DDG
DDG H
J
L
N
O
T
V
DDH B
C
G
N
O
DDJ
DDJ J
K
S
T
W
X
(By number)
Single (usually assumed)
Double, binary
Visual
Spectroscopic
Astrometric
Eclipsing = eclipsing variable = extrinsic variable
= algol type
See also Variable stars
Individuals, A/Z
Triple
Multiple
DDK M
N
O
Proto-stars, globules
Main sequence stars
Giants
Novae = eruptive variables
Recurrent
Individual novae, A/Z
Supernovae
Individual supernovae, A/Z
Dwarfs
Dark spheres
Q
S
T
V
Individuals, A/Z
DDL N
Q
R
DDT
DDO
Regular, short period
Cluster variables
Individual types, A/Z, e.g.
Cephoid variables DDK OC
RRLyrae variables DDK OR
Semi-regular, long period
Irregular
Flare stars
DDL
DDR
“
(By stage)
Population I stars
Population II stars
(By radiation phenomena)
Variable stars = intrinsic variables = pulsating stars
* For Eruptive variables see Novae
For Eclipsing variables see Binaries
DDK
DDR
High energy bodies & systems
See also Radiation DCR
Radio sources = Radio galaxies
Quasars
Pulsars
7
DDS
DDS
[Pulsars]
DDL S
T
DDM
Light sources
Optical quasars
GALAXIES & GALACTIC GROUPS = Stellar systems
DDM F
H
J
K
Intergalactic space = Interstellar space
HI region (Interstellar clouds)
HII region
Ionization fronts
DDN
Nebulae
See also Cosmic matter
Extragalactic nebulae, spiral nebulae see Galaxies
DDN N
P
R
S
T
DDO
Associations
Individuals, A/Z - e.g.
Cygnus II DDP C
DDQ
Clusters
See also Stars by number DDG
Constellations
Individuals, A/Z
DDT B
D
E
G
H
J
Galaxies = Extragalactic nebulae
(By configuration)
Spiral
Elliptical
Irregular
Compact
Individual, A/Z
N
Galactic groups, clusters of galaxies
DDW
DDW N
NV
DDU
Open
Globular
Individual, A/Z - e.g. DDR M67
DDR Y
DDS
DDV
DDV
Emission nebulae
Reflection nebulae
Planetary nebulae
Dark nebulae
Ring nebulae
Individuals, A/Z
DDO Y
DDP
DDQ R
S
DDR
DDE
DDG
Individual groups other than the Local Group, A/Z - e.g.
DDV M81
DDV M101
Local group
[Nebulae]
Individual, A/Z - e.g.
Magellanic clouds = Nubeculae
DDW NVN
8
DD
DDE
DDU
[Nebulae]
[Magellanic clouds]
DDW TB
TJA
TJT
DDX
DDX V
[Galaxies]
Andromeda
Triangulum
The Galaxy = The Galactic space
Milky Way
DDY
DDY B
P
S
Stars other than Sun, A/Z - e.g.
Barnard’s star
Proxima Centauri
Sirius
DDZ
Sun and Solar System together
DF
* When qualifying DE by earlier concepts follow
the same rule as given at the beginning of DD i.e. add divisions of DD straight on to DE
without using the second ‘D’ - e.g. DEG O
Surface of the Sun (not DED GO).
DDZ E
Interplanetary space
DE
Sun
DE
DF
Planets & satellites
* An alternative to DF for existing users of
BC, minimising change, is given at the
end.
DF
DFA/DFC
DFD
Divide like DA/DC
Chemistry
DFE G
M
P
Q
S
V
X
(Parts)
Geology
Mineralogy
Core, nucleus
Subsurface
Surface = Periphery
Soils, dust
Runnels
DFF B
D
E
G
J
L
M
N
O
Plains
Depressions
Craters
Elevations, protuberances
Topography, landmarks, areas
Envelope
Atmosphere
Lower
Upper
9
[Atmosphere]
[Upper]
DFF Q
R
S
Meteoric
Corpuscular
Electronic
DFF J
M
(Special to comet)
Coma
Tail
DFG
DFG M
DFH
DFJ
Meteors & meteorites
Meteorites
Satellites
Individual, A/Z
DFX
DFL
Comets
Individual, A/Z
DFM
DFN
DFO
Planets
Mercury
Venus
Earth see DFT
Mars
Deimos
Phobos
Asteroids, planetoids
Jupiter
Saturn
Uranus
Neptune
Pluto
DFP
DFP D
P
DFQ
DFR B
D
F
H
P
DFT
DFU
Earth
Moon
DDY
DFK
DFH/I
DFF/G
DFD/E
DFC
DFT
DFU
* Alternative schedule for DF Planets & satellites for existing BC
users, minimising change.
DF
DFA/DFC
DFB
DFC/DFD
DFD U
DFF B
D
F
DFH
DFJ
DFL
DFM
Planets and satellites
Divide like DA/DC
Chemistry (as DD)
Divide like DFE/DFF above - e.g.
Atmosphere of planets & satellites DFD M
Divide like DFG/DFM above - e.g.
Satellite atmosphere DFD UDM
Pluto
Neptune
Uranus
Saturn
Jupiter
Asteroids
Mars
Earth see DFT
DF
DFC
DFD/E
DFF/G
DFH/I
DFK
DFL
DFM
10
[Mars]
[Earth see DFT]
DFP
DFR
DRT
DRU
Venus
Mercury
Earth as planet
Moon
DFP
DFR
DFT
DFU
11